We have recently discovered a glycopeptide factor in liver which appears to mediate the effects of diabetes and insulin administration as well as the effects of dietary manipulations on levels of phosphofructokinase in this organ. We propose to measure the distribution of the factor and the extent of its ability to interact with other enzymes, to determine the role of insulin and/or glucose in the mechanism of regulation of the levels of this factor, and to determine the structure and sequence of the constituents of the factor.